1. The Field of the Invention
The present invention relates generally to video processing in a computer system and, more particularly, to converting a video signal to another type of video signal for display in a computer system. More particularly still, the present invention relates to a video processing system that provides resolution enhancement of a signal being converted from one standard to a second standard to be displayed on the computer system.
2. Prior Art
Personal computer systems are becoming much more versatile in their functionality and utilization. Most personal computers now include multimedia capabilities, such as being able to handle either video or audio input and output functions, or both. In handling selected video input sources, a typical computer normally operates in a digital mode and requires the input source material to be in digital form. The computer system, otherwise, must be able to convert non-digital information into digital information for further processing and subsequent output. Specifically, a typical multimedia computer will be able to accept various input sources and then convert them into digital form for output on a digital monitor normally associated with a computer system. During the transformation from one standard, such as an analog signal, to a computer-compatible standard, meaning digital signal, degradation occurs to the signal during the transformation process. This degradation has typically been endured for the sake of at least having the information available and useful to some degree; however, just as computer systems have gotten faster and more efficient as well as better at handling with their traditional features, it is desired that even the multimedia applications, especially in the video mode, keep up with the improvements so that the quality of the output signal, regardless of its initial input source, is at a very high level as if the output signal had initially been obtained from a high-quality input source.
The typical multimedia setting of converting from one video standard to another is that of input of an analog signal into a computer system and then conversion of it for digital output on the monitor. One problem with analog signals is that typically they are in an interlaced format, meaning that half the screen lines, for example, the odd lines, are scanned first and then the remaining half of the scan lines, typically the even lines, are scanned second in such a fashion so that the two screens are interlaced together in order to enhance resolution. This is a problem since most computer video monitors are progressive scan, which results in better resolution. The analog image must be converted to display on the progressive monitor. When analog images are converted field by field, since each field has only half the information that is otherwise required for display, a very poor, if not unacceptable, image is obtained with a conversion from analog to digital.
Additionally, analog signals typically refresh at one rate while the computer output, which operates on a progressive scan monitor, refreshes at a different rate. Converting from one refresh rate to the other refresh rate may result in field dropping or repetition which results in jerky motion.
Another problem is that the resolution is different between the analog signal and the video display monitor. Since the resolution is different, the solution has typically been to expand the field or shrink the field in order to compensate for the different resolution standards between the analog and digital environments.
Accordingly, what is needed is a video processing system for use in a computer system that is able to receive analog video signals and convert them to digital video signals regardless of refresh rates and resolution differences. This system should be able to perform this conversion without the resulting degradation previously described above.